1. Field of Invention
This invention relates generally to an irradiation chamber wherein a stream of infected blood flowing through the chamber is exposed to ultraviolet radiation to destroy microorganisms carried by the stream, and more particularly to a chamber of this type in which the blood stream flows through a labyrinthine passage which acts to create internal displacements within the blood stream to ensure that all portions thereof are adequately exposed to radiation.
2. Status of Prior Art
Blood, the circulating fluid of the human organism, is an aqueous solution of protein salts and organic substances containing various types of cells and cell products in suspension. The fluid portion of blood is its plasma, whereas the cells and cell products constitute the solid portion.
It is known to treat blood stream infections by subjecting the stream to ultraviolet radiation, for UV rays have bactericidal properties that are effective against the microorganisms responsible for the infection.
Of prior art interest in regard to such treatment is the blood irradiation chamber disclosed in an article by E. K. Knott in the August 1948 issue (Vol. LXXVI-No.5) of the American Journal of Surgery, entitled "Development of Ultraviolet Blood Irradiation."
The circular chamber disclosed in this article whose approximate dimensions are 2 inches in diameter and one inch in thickness, includes a quartz window transparent to UV, under which are baffle plates that fit flush against the window. These baffle plates are arranged to define a labyrinthine passage which snakes from the inlet to the outlet of the chamber.
The baffle plates which are in parallel relation create a series of interconnected flow channels, so that in the course of flow the stream passes around the end of each channel into the next channel in the series.
The circuitous path of the blood stream produces some degree of turbulence as the stream flows through this path, and causes the blood to flow towards and away from the quartz window. It also acts to minimize the creation of regions in the chamber in which there are stagnant pools of blood.
In a Knott irradiation chamber, the quartz window is transparent to UV rays in the range of 1400 to 4000 Angstroms. The function of the chamber is to expose to the stream of blood coursing through its passage to UV rays for a period sufficient to destroy the microorganisms responsible for the infection, but without damaging the cells and cell products in the blood.
Ideally, in a Knott chamber, there should be uniform exposure to UV radiation of each fraction of the blood flowing therethrough so that no portion of the stream remains inadequately treated. But the Knott chamber falls short of this ideal, as a consequence of which the treated blood will not be infection free.
Also of prior art interest are the following patents which show Knott-type blood chambers U.S. Pat. Nos. 2,309,124; 2,308,516; 2,314,281.